alternative..??
I had a 72 K5 with a leaky gas tank too...I lucked out and found one in another mint truck just like mine a guy had ,he got drunk on easter sunday and T-boned a fire hydrant,and totalled the truck..I bought the gas tank,complete 4 spd setup to replace my TH350 setup,brake booster,etc..guy had just replaced the tank about a year earlier,with a genuine GM one he searched dealerships for across the country..one in Kansas had one!..
But while I was searching for a tank (and this was in 1984 or so!)--they were not readily available even then!--GM stopped making them after 10 years,and for some reason aftermarket companies focused only on 73-87 K5 tanks..J.C Whitney had both steel and poly ones listed in their catalog at the time..IF you had 300-400 bucks to buy one.(It might be they still list them maybe???).---so I started looking in boneyards for a stock one,or anything close that might fit..
I found chevy "G" series Vans had a very similar tank,in dimentions, and the gas filler came out in the same area..and Dodge Vans,and Ramchargers in the late 80's had poly tanks,and the Ramcharger one looked like it would fit in with modifications...but the sender unit from a Dodge won't jive with a Chevy gauge..(I had a Dodge poly 40 gallon tank in my 74 GMC--it made my gas read read backwards !--empty when full,and full when empty!--but it was accurate!

)...so maybe if you cant find or afford the bolt in tank,one of those might get you by...
